Don't take it personally but it's not a question of people wanting you to lose but it's human nature for everyone to want to back the underdog.
If you talk about memorable cup finals, the ones where the underdog wins are always best remembered.
Just think of The 1973 FA Cup Final, Sunderland beating the then mighty Leeds, Ian Porterfield and Jim Montgomery.
It's the romance of the cup.
Having said all that, I expect you to stuff Sunderland today.